In late August of 2015 the invasive algae, Starry Stonewort (Nitellopsis obtusa) was confirmed in Lake Koronis at the Highway 55 public boat access. It was the first time that this Aquatic Invasive Species was confirmed in Minnesota.
Starry stonewort is a stringy algae that can grow from two to twenty-five feet deep, can overwhelm native plants and prevent navigation. Starry stonewort prefers gravel substrates and can quickly overwhelm spawning beds. Because it is not a vascular plant, chemical treatments are both expensive and relatively ineffective. It spreads easily from either plant fragments or by the small bulbils it produces.
Michigan discovered starry stonewort in 2005 and took no direct action to contain it. Today over 1,000 Michigan lakes are infested.
When starry stonewort was confirmed in Lake Koronis, Minnesota Lakes and Rivers Advocates, the Statewide AIS Advisory Committee, the Lake Koronis Association, City of Paynesville, and Stearns County all asked the MN DNR to close the access where it was discovered until the infestation at that access could be effectively treated. The MN DNR left the access open, performed an algicide treatment late fall of 2015 and again in the early spring of 2016, but had little effect. In 2016 the MN DNR permitted a number of fishing tournaments at the site without requiring outgoing decontamination. By 2021, sixteen lakes (31 public accesses) were infested. Lake Koronis now spends about $200,000 annually on starry stonewort mitigation to keep the public access usable.
Starry stonewort spread in the Upper Midwest.
Actions Taken
Following the discovery of starry stonewort in 2015, the Lake Kornois Association contacted Dr John Rodgers, Clemson University, a nationally recognized leader in starry stonewort research. Working with Dr. Rogers, the Minnesota Aquatic Invasive Species Research Center, the Stearns County AIS task force, the Lake Koronis Association researched a variety of treatment methods, including hand pulling, mechanical removal, algicide treatments and a combination of methods. After a few years they had developed a treatment protocol that reduces the biomass enough to preserve navigation and recreation on the lake.
Since 2017 the Minnesota Aquatic Invasive Species Research Center and Extension Service has run a robust early detection program called “Starry Trek.” Each year over 200 volunteers survey hundreds of high risk MN lakes. Early detection of starry stonewort, before it becomes widely distributed, has proven to improve outcomes and cost effectiveness. The Stop Starry program is working to support MAISRC Starry trek event, and early detection programs at lake associations across Minnesota.
The Stop Starry containment strategy is based on research, replicated by MAISRC and Minnesota Sea Grant, which found that:
- Most boaters knew the risks of AIS and the steps they needed to take to prevent spread, but less than half took all the actions required. The reason was lack of the tools they needed at the access where they needed them.
- Once a new AIS is introduced into an area, lakes within 50 miles of the infested lake are at significantly higher risk
By providing free to use boat cleaning equipment at the access, where boaters need it, and increasing local awareness, engagement and organizing, we can lower the risk of spread to the other lakes in the area.
MLR Launches a Containment Strategy
In 2021 MLR applied for a grant from the Environment and Natural Resources Trust Fund, ENRTF to initiate a containment strategy. To date the Stop Starry Program partners have:
- Partnered with Tribes, Local Government Units, lake associations and resort owners to instal waterless boat cleaning stations at starry stonewort infested accesses in MN and support use of these tools with community education, education and outreach,
- Expand a base of active citizens to create a “civic value” to Clean, Drain and Dry,
- Initiate focused community based social marketing campaigns to Clean, Drain and Dry,
- Rank by risk and assess boat ramp signage. Update as needed.
- Initiate and expand aggressive lake monitoring to find any new infestations early.
- Develop and test new control measures including Diver Assisted Suction Harvest, DASH, burlap and other screen barriers over starry stonewort beds, and repeated hand pulling. Early results show promise.
By the end of the second year, 2023, over 22 thousand boaters had used these tools. DASH has proven to be an effective treatment and testing of other strategies will be expanded to more locations during open water season 2024.
Last legislative session the Minnesota Legislature appropriated $250,000 to MLR to cover any accesses that are found to be infested with starry stonewort and expand our civic engagement strategies to all AIS efforts in Minnesota.